Sanogo was available as a free agent following his departure from Auxerre at the end of last season.
The 20-year-old scored 11 goals in 24 appearances during his time in Ligue 1, having joined Auxerre as a 14-year-old.
"Sanogo is a good young signing for us," said Gunners manager Arsene Wenger on the club's official website.
"He has shown that he has potential with his recent performances for Auxerre and also for the France Under-20 side.
"We are looking forward to Yaya joining us and continuing his promising development."
Sanogo is currently playing in the Under-20 World Cup, where he has scored in two of his country's three games to help them qualify for the knockout stage.